Friction twist tangling of yarns

ABSTRACT

Filaments of multifilament yarn are intermingled by being mechanically false-twisted. The resulting yarn is compact and coherent, having handling properties equivalent to a twisted yarn.

United States Patent 1191 i i 1111 3,816,993

McWaters June 18, 1974 [5 FRICTION TWIST TANGLING 0F YARNS 3,043,084 7/1972 Smith... 57/77.4 x [751 lnvemon Talmadge Mcwaters, Pensacola, 31352932, 352? 555321'1:ijjjiiiiiijiji....111131:2313333,?

Fla.

73 Assi n e: Mensa to Com an St. Lo ,M r 1 g e n p y, ms 0 Primary Examiner-Donald E. Watkins Filedi 1972 Attorney, Agent, or Firm-Kelly O. Corley 211 App]. No.: 301,394 1 [52] US. Cl 57/157 R [57] ABSTRACT [51] Int. Cl D02g 3/00 Field of Search... 57/34 R, 34 HS, Filaments of multifilament yarn are intermingled by 157 157 T5 being mechanically false-twisted. The resulting yarn is compact and coherent, having handling properties [56] References Cited equivalent to a twisted yarn.

UNITED STATES PATENTS 2,908,133 10/1959 Brown 57/77.4 5 Claims, 8 Drawing Figures YARN 3 O U R C E MECHANICAL -24 INTERLACER PATENTEBJBI I a m I YARN #22 SOURCE MECHANICAL -24 INTERLACER FURTHER r" l PROCESS l L l 1 FRICTION TWIST TANGLING OF YARNS The invention relates to the art of interrningling fil manets in a continuous filament compact non-bulky) yarn. More particularly, the invention relates to aprocess wherein the intermingling is accomplished by mechanically false-twisting the yarn.

It is known in the art that the handlingproperties and. threadlineintegrity of a continuous filament yarn'having no twist or only a small amount of twist can be improved by modifying the relationships of the filaments:

to one another. Guyot (U.S. Pat. No. 2,702,982) alternately twists the yarn so that thetyarn wound on the package has successive sections of opposite twist. While the alternate twist approach does improve the integrity of the yarn bundle so that the yarn will perform as though it contains a substantial amount of real twist, it also introduces certain visible and objectionable optical patterns into certain fabrics formed from such yarn.

A number of patents have suggested that the filaments be intermingled by subjecting. the yarn to the action of a highly turbulent fluid jet, as typified by Bun ting, ctal. US. Pat. No. 3,110,151. These pneumatic intermingling processes, while generally operable with yarns having a relatively low denier per filament, are' not always entirely satisfactory when used withyarns having more than about 3 or 4 denier perfilament, or more than about 100 total denier. The filaments of yarns having relatively high denier per filament and relatively high total denierare particularly difficultto satisfactorily intermingle.

Further drawbacks to the pneumatic interlacing. processes arethe relatively highcost of the air or other fluid consumed, various problemsassociated with critical alignment of theyarn with the jet; pluggage of the orifices, etc.

US. Pat. No. 3,404,525 discloses that a coherent compact yarn can be made without interlacing or inter mingling of the filaments by imparting to the yarn a low degree (between 0.25 and 2.5 turnsper inch) of twist liveliness or torque. This is disclosed as accomplished by applying false twist during the drawing operation so that the yarn is helically drawn, or by false twist heat setting of a previously drawn yarn. The resulting torque in the yarn decays with time during storage, and accordingly the coherency of the yarn decreases. By way of contrast, yarns wherein the filaments are intermingled do not lose their coherency upon storage.

According to the presentinvention, these and other disadvantages of theprior art are avoided by mechanically false-twisting the yarn, as more fully set forth below.

A primary object of the invention is to provide a novel process for intermingling the filaments in a multifilament yarn.

A further object of the invention is to provide a process of the above character wherein the filaments are intermingled by being false-twisted in the absenceof heat-setting conditions.

A further object of the invention isto provide a process of the above character wherein the filamentsare intermingled by frictional contact with a surface moving transverse to the direction in which the yarn travels.

Other objects will be obvious-from: the.following.de-.

tailed description taken together with the accompanying drawings, wherein:

FIG. 1 is a box diagram.illustrating the.process; FIG. 2 is a perspective view of a first type. of mechanical interlacer;

FlG. 3 is a sectional. viewttaken. alongthelinew3 -3.

in FIG. 2; and

F IGS. 4-8Iare perspective. views of other exemplary mechanical interlacers accordingdo the invention.

As shown generally in FIG." 1," yarn20-is.fed from a source 22 through mechanical interlacer 24x0 apparatus 26 for performingpfurther processing. such as winding the yarn on a package. Source. 22llpreferably includesa drawing operation so. that yarn 20 has already beendrawn before being subjected to the present process.

According to the invention, mechanical interlacer 24 mechanically false twistsyarn 20by subjecting the yarn to frictional contact witha surface movingin a direction transverse to the direction of movement of the.

lacer 24, the filaments on thevoutside of the yarn bundle travel a longerdistance thanthose near thecenter of the bundle since they must follow longer helical paths. This places the outerfilaments undera higher:

tension thatthose near thecenten Thefilaments migrate in order to reduce these tension differences, those; outerfilaments under relatively hightension tending to force their way toward the interior ofithe bundle, movingaside those filaments near the center of the bundle. As a result, any individual filament will successively be located on the outside of the bundle, then in the interior, then outside again, etc. Asthe temporary twistis removed in interlacer 24, the filaments do not return to their original positions, but are restrained byfrictional forces among themselves, and remain intermingled.

Any of the false twistingdevices which have been suggested for. use in false twisting heat-setting (texturing) are suitable in some degreefor use in the present.

invention, so long as the false twisting device frictionally contacts theyarn with a surface movingin a direction transverse to the direction of movement of the yarn so as to roll theyarn about the yarn axis.

So-called friction twisters are preferred over the conventional false twist spindles which can insertonly one turn of twist for each revolution of the spindle. FIGS. 2-8 illustrate exemplary friction 'twisters of the preferred type wherein each revolution of thefalse twisting'device can insert several .tums twist in the yarn.

The device shown in FIGS. 2and SQIS of the general type disclosed in US. Pat. No. 2,936,567. As illustrated, device 24 is an annular bushing driven to rotate.

about its axis by means. not shown. Yarn 20 passes through the bushingand bears against the inner annular: surface. As the bushing makes one revolution, yarn 20 can make a large numberof revolutionsabout its axis, since the inner periphery of the bushing is large compared tothe yarn circumference.

FIG. 4 schematically shows aifalse twisting mechanism of the general type disclosed in US. Pat. No.

3,287,890, wherein interleaved discs 28 and 30 rotate in the direction shown. Yarn 20 rides in the notch or trough formed in the regions where discs 28 and 30 intermesh, and is false twisted by frictional contact with the discs peripheries.

FIG. schematically illustrates that yarn 20 may be false twisted by frictional engagement with the periphery of a single rotating disc 28. Suitable guides 32 are provided for locating the yarn. The illustrated pigtail guides are merely exemplary.

A plurality of yarns may be processed simultaneously by a single false twisting device, as shown in FIG. 6. In this embodiment, device 24 includes belt 34 supported and driven by rolls 36. Yarns 20 frictionally engage the upper surface of belt 34, and are false twisted thereby.

Each of the false twisting devices in FIGS. 2-6 are positively driven by separate non-illustrated means. However it is possible to provide a false twisting device which is driven by the yarn, as shown in FIGS. 7 and 8. In FIG. 7 an idler (undriven) roll 38 having a curved flange 40 is located adjacent a separator roll 42. The axes of rolls 38 and 42 are not parallel, so that adjacent wraps of yarn 20 are separated. Yarn 20 is fed to roll 38 at an angle such that yarn 20 rolls against and is false twisted by flange 40 before touching the cylindrical portion of roll 38.

In FIG. 8, idler roll 44 is provided with a concave annular surface. Generally similar to the FIG. 7 device, yarn 20 is red to roll 44 at an angle such that yarn 20 rolls against and is false twisted by the concave surface of roll 44.

The false twisting devices shown in FIGS. 7 and 8 can be positively driven if desired.

Theoretically, the process of the invention can be applied to any continuous filament yarn having at least three filaments, although useful results normally are obtained only with yarns of at least filaments. The process is practicable at any speed at which the yarn can be forwarded. Yarn speeds between 10 and 5,000 yards per minute are presently practical. Speeds are limited by the capabilities for winding the yarn, and not by limitations in the present process.

To produce the compact coherent yarns according to the invention without introduction of undesirable twistliveliness or torque into the yarn, it is essential that the yarn not be appreciably drawn in the false twisted configuration, and that the yarn not be subjected to effective heat-setting conditions while in the false-twisted configuration. Avoidance of a troublesome amount of drawing is achieved by maintaining the tension on the false-twisted segment of the yarn between 0.01 and 1.0 grams per denier, and preferably between 0.08 and 0.5 grams per denier. The tension downstream of interlacer 24 will normally be somewhat higher than the tension in the false-twisted region.

It is also essential that the yarn not be subjected to effective heat-setting conditions while it is false twisted, since otherwise the yarn will be textured. Heat setting can occur if the false twisted portion of the yarn is heated to a sufficiently high temperature for a sufficient time period and then cooled to a sufficiently low temperature before the false or temporary twist is removed. These conditions are already known or are readily ascertainable for yarns made from various polymers. Thus nylon 66 is conventionally textured by heating the temporarily twisted yarn to a temperature of,

for example, 180 C. for a time period of at least several tenths of a second, then cooling to below 100 C. before the twist is removed. This results in a well textured yarn, as is well known in the art. Such heat-setting conditions must be avoided according to the present invention. This may be done by several methods. If the yarn in the twisted region is sufficiently cool, no noticeable texturing or inducement of residual torque will occur. However, texturing or inducement of residual torque can be avoided even if the yarn fed to the twisted region is hot by either untwisting before the yarn has sufficiently cooled or by cooling the twisted yarn before the molecules have rearranged into the twisted configuration. As an example, denier 34 filament nylon 66 yarn heated to 180C. by a prior process is fed to the false twist zone at a speed of 3000 yards per minute, the false twist zone being air at 70C. and the length of the false twist zone being about one yard. The false twist device of FIG. 4 is used, the discs having diameters of about 2% inches and rotating at 10,000 rpm. The filaments of the yarn are well-intermingled, giving a zerotwist yarn with coherency and handling properties equivalent to those of a yarn with one to two turns per inch twist. The yarn has no discernable torque. Avoiding texturing or the setting of objectionable torque into the yarn can readily be achieved by one skilled in the art. Residual torque is less than 0.25 turn per inch in yarns according to the invention, and preferably is substantially zero, the measurement being made four hours after the yarn is collected on the bobbin. To measure residual torque, a one-yard sample of the yarn is unwound from the bobbin, the free end of the yarn being held to prevent it from twisting. A small tab (one-half square inch) of cellophane tape is attached to the free end. The yarn sample is held vertically with the free end in the lowermost position. The free end is then released, and the revolutions made by the free end in two minutes are counted. The number of revolutions divided by 36 equals the turns per inch of residual torque. During this test, the ambient temperature should be between 65 and F., and care must be taken that the yarn is not subjected to drafts or air currents which might influence free rotation of the free end of the yarn.

The present process is particularly useful in intermingling the filaments in yarns having more than three denier per filament. For example, a drawn nylon 66 yarn having a total denier of 200 and 34 filaments is forwarded at a speed of 3000 yards per minute and under a tension of 20 grams to a windup mechanism. Various types of pneumatic intermingling devices and process conditions are employed in an effort to satisfactorily intermingle the filaments. The shortest average distance attainable between filament tangles located by a pin or hook inserted into the bundle under the hookdrop test specified in US. Pat. No. 3,110,151 is too long for commercial acceptability by a factor of 3. The pneumatic intermingling devices are then replaced with the FIG. 4 apparatus under the conditions specified in the preceeding paragraph. The distance between tangles is now observed to be within the range of commercial acceptability. Similar results are obtained in a comparison of pneumatic tanglers with mechanical false twisters on polyethylene terephthalate yarn having total denier and 34 filaments.

The transversely moving surface which frictionally engages the yarn for imparting false twist thereto should have a relatively high coefficient of friction with the yarn. In most cases, the surface should be made of a resilient rubbery material, such as an elastomeric polyurethane. However a harder surface such as steel or the like can be used in many cases. The coefficient of friction, yarn speed and tension, and surface speed of the false twisting device should be chosen such that at least 5 and preferably or more turns per inch false twist be imparted to the yarn upstream of the false twist device. The twist level is determined by trapping a sample length of the running yarn, counting the number of turns in the sample, and dividing the number of turns by the length in inches of the untwisted yarn sample. The twist level and tension are such that the yarn does not twist double.

I claim:

1. A process for interlacing the filaments in a multifilament yarn bundle, comprising in combination:

a. forwarding said yarn bundle at a given speed in a given direction at a tension between 0.01 and 1.0

grams per denier;

b. applying to said yarn bundle in the absence of heat-setting conditions a unidirectional false-twist of at least 5 turns per inch of said yarn, said step of applying false-twist being performed by subjecting said yarn bundle to frictional contact with a surface moving in a direction transverse to said given direction; and

c. removing said false-twist from. said yarn bundle.

2. The process defined in claim 1, wherein said yarn bundle is drawn prior to being false twisted.

3. The process defined in claim 1, wherein said yarn bundle while being false twisted is under a tension of between 0.07 and 0.5 grams per denier.

4. The process defined in claim 1, wherein said surface is positively driven.

5. The process defined in claim 1, wherein said surface is driven by said yarn bundle. i i 

1. A process for interlacing the filaments in a multi-filament yarn bundle, comprising in combination: a. forwarding said yarn bundle at a given speed in a given direction at a tension between 0.01 and 1.0 grams per denier; b. applying to said yarn bundle in the absence of heat-setting conditions a unidirectional false-twist of at least 5 turns per inch of said yarn, said step of applying false-twist being performed by subjecting said yarn bundle to frictional contact with a surface moving in a direction transveRse to said given direction; and c. removing said false-twist from said yarn bundle.
 2. The process defined in claim 1, wherein said yarn bundle is drawn prior to being false twisted.
 3. The process defined in claim 1, wherein said yarn bundle while being false twisted is under a tension of between 0.07 and 0.5 grams per denier.
 4. The process defined in claim 1, wherein said surface is positively driven.
 5. The process defined in claim 1, wherein said surface is driven by said yarn bundle. 